On Thu, Mar 13, 2014 at 4:18 PM, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > On Thu, Mar 13, 2014 at 03:32:01PM +0100, Linus Walleij wrote: >> > + case ACPI_IO_RESTRICT_OUTPUT: >> > + gpiod_direction_output(desc, pull); >> >> Can you explain why the fact that the line is pulled down affects the >> default output value like this? I don't get it. > > That's the thing - ACPI doesn't tell us what is the initial value of the > pin. There is no such field in GpioIo() resource. > > So I'm assuming here that if it says that the pin is pulled up, the default > value will be high. OK! So exactly that statement is what I want to see as a comment in this switch case. >> > + if (function == ACPI_WRITE) >> > + gpiod_set_raw_value(desc, !!((1 << i) & *value)); >> >> What is this? How can the expression !!((1 << i) possibly evaluate to >> anything else than "true"? I don't get it. Just (desc, *value) seem more >> apropriate. > > We are dealing with multiple pins here. So for example if > agpio->pin_table_length == 2 and *value == 0x2 we get: > > i == 0: !!((1 << 0) & 0x2) --> false > i == 1: !!((1 << 1) & 0x2) --> true Yeah, Alan already pointed out my parse error... this is OK. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
